Some scholars permit paying expiation before breaking the oath

Hazrat Ibn Aun states that Hazrat Muslamah bin Makhlad and Hazrat Salman considered it permissible to pay the expiation even before intercourse.

Hazrat Ibn Sirin narrates that Hazrat Abu Darda called a slave and set him free, and later when he broke an oath, he made that slave the expiation for that oath.

Yunus narrates that Hasan used to offer expiation even before taking an oath.

Hazrat Ash'ath states that Hazrat Ibn Sirin used to pay the expiation even before breaking the oath.

Ibn Aun states that Muhammad used to pay the expiation even before taking an oath, and Hasan would take an oath and then pay the expiation.

12704 - And Al-Hasan used to say: He breaks his oath and then offers expiation.

Hazrat Abdullah bin Kathir narrates that he heard a person ask Hazrat Jabir bin Zaid: "I took an oath, but then I see something better than it, so what should I do?" He replied: "Pay the expiation for your oath and intend what is better."